How to do"cut-out shape" or slice within a slice?

[IsocellatorComm]

There may be an easy way to do this, but so far I'm still trying to figure it out....

Objective:
I'm looking to place a custom shaped slice over another slice, and have seperate masked/cropped video within both. Let's say a star shape enclosed in a large triangle. I would like the video within the star shape and the triangle to not be distorted or re-shaped, just masked or cropped into the needed shapes.

This is probably pretty basic, but once I create the higher-order mask or crop, it blanks the layers of the lower-order slices as well....

[Zoltán]

I would do that on the layer(or clip) level, either with pre-created png masks, or using multiple keystone crop/mask effects.

https://resolume.com/manual/en/r4/masks

[Oaktown]

Create your masks in Photoshop as PNG files with an alpha channel and size them to match the media you're masking so that you can precisely place it in your composition. Then follow Ravensc's advice and drop the PNG masks on layers or clips and you're all set